The present application claims the right of foreign priority of German Application No. DE 100 50 691.7, filed Oct. 13, 2000, the subject matter of which is incorporated herein by reference.
The invention relates to a method and an apparatus for simulating a shot fired from a gun that fires ballistic projectiles at a target, preferably an earth-bound, moving or standing target.
In a known apparatus for firing simulation, referred to as a two-way simulator (DE 22 62 605 A1), and utilizing a practice firing device operating with laser pulses, a laser pulse transmitter is secured to the barrel of the gun and its transmitted laser-pulse sequence reaches a target through the manual aiming of the gun at the target by a gunner. If the gunner perceives the aiming process as correct, he actuates the trigger of the gun. This initiates an automatic process in which a transmitter control switches on the laser transmitter for a duration of a few milliseconds. The laser pulses impact reflectors disposed on the target, from where they are reflected onto a position-sensitive detector on the gun barrel. A range calculator calculates the target range from the transit time of the reflected laser pulses. An angular-position calculator simultaneously determines the angular deviation between the bore axis of the barrel and the center of gravity of the reflected laser radiation. A flight-time calculator determines the theoretical projectile flight time. Over the course of the projectile flight time, the laser transmitter transmits a further laser-pulse sequence, and the angular-position calculator recalculates the angular deviation between the bore axis and the center of gravity of the laser radiation.
A range calculator uses the target range and type of ammunition to calculate the correct range setting. In accordance with this correct setting, a point-of-burst position calculator uses the elevation-angle course of the target at the beginning and end of the projectile flight, the elevation aiming angle of the barrel at the time of firing and the range, to calculate the angle of elevation of the point of burst or point of impact. Analogously, the azimuth-angle course of the target at the beginning and end of the projectile flight, the lateral-pivot angle of the barrel at the time of firing and the range, are used to calculate the lateral position of the point of burst.
The point-of-burst position calculator is connected to an encoder that is programmed with respect to the type of weapon and ammunition, and is connected to the range calculator. The encoder controls the laser transmitter such that the transmitter transmits a second, encoded laser-pulse sequence that differs from the first laser-pulse sequence, and contains information about the range, the lateral and elevation-related deviations of the point of burst, and the type of ammunition and weapon. This laser-pulse sequence impacts a detector disposed on the target, to which an impact receiver, a decoder and an impact-data calculator are connected. The impact-data calculator uses the transmitted information to determine whether the weapon was effective in terms of the type of ammunition used, and calculates the effect of the detonation through a comparison between the expansion of the target in the firing direction and the deviation of the point of burst in the lateral and elevation directions.
It is the object of the invention to provide a method for firing simulation of the type mentioned at the outset, which permits larger ranges while adhering to the guidelines for visual detectability of the used laser, and also does not fail when the weapon fires at a group of closely-clustered targets. Moreover, an apparatus for firing simulation that operates in accordance with the method is intended to be produced inexpensively.
The above object is achieved according to a first aspect of the invention, by a method for simulating a shot fired from a gun for ballistic projectiles at a target, preferably an earthbound, moving or standing target, which comprises: aiming a sight, whose line of sight extends parallel to the bore axis of the gun, at the target with a setting of a horizontal course (lead) and a vertical course (elevation) of the line of sight from the target; then manually activating a trigger on the gun to initiate a simulated firing of the gun by transmitting a first laser beam including a plurality of laser pulses corresponding to a fictively fired projectile; calculating a trajectory of the fired fictively projectile; continuously determining the deviations of the trajectory from the instantaneous line-of-sight orientation at the firing time; pivoting the first laser beam by pivot-angle values that correspond to the trajectory deviations; measuring the transit time of the laser pulses reflected by the target and using the transit times to determine the target range (r); comparing either the time that has passed between the firing time and the reception of the reflected laser pulses to the flight time of the fired virtual projectile calculated for the target range (r), or comparing the actual pivot-angle values of the first laser beam relative to the instantaneous line-of-sight orientation at the firing time, with the actual pivot angle values being associated with the target range (r), to the theoretical pivot-angle values of the first laser beam relative to the instantaneous line-of-sight orientation at the firing time, with the theoretical pivot angle values having been calculated from the trajectory data for the target range (r); if the compared values match within a tolerance range, transmitting a second laser beam comprising encoded laser pulses in the transmission direction last traversed by the first laser beam, with the encoding of the second laser beam containing information about firing data of the gun, including the type of ammunition and weapon, and the identity of the gunner; and, when the second laser beam is received by one of a plurality of detectors distributed over the surface of the target, calculating impact damage from the position of the receiving detector on the target.
The above object is achieved according to a further aspect of the invention by an apparatus for simulating a shot fired from a gun for ballistic projectiles at a target, preferably an earthbound, moving or standing target, which apparatus comprises: a gun having a sight whose line of sight is permanently set parallel to the bore axis of the gun, and a trigger for initiating the fictively fired projectile; a laser transmitter, which is fixedly coupled to the gun, for transmitting a first laser beam comprising laser pulses, and a second laser beam comprising encoded laser pulses, with a temporal offset and in the same direction as the first laser beam; a control unit, which is activated by the trigger, and upon being activated, causes the laser transmitter to transmit the first laser beam; a detector that is permanently connected to the gun for receiving the laser pulses of the first laser beam that are reflected at the target; a transit-time measuring element, which is disposed downstream of the detector, for measuring the transit time of the reflected laser pulses of the first laser beam; a range calculator for calculating the target range (r) from the transit time; a trajectory calculator, which is connected to the range calculator, for calculating trajectory data of the fictively fired projectile; a plurality of detectors that are distributed over the target surface and configured to receive the second laser beam; and evaluation electronics, which are connected to the detectors, for calculating impact damage; a deflection apparatus for pivoting the transmission direction of the laser beams connected to the trajectory calculator. When the first laser beam is transmitted, the trajectory calculator continuously calculates the deviation of the trajectory from the instantaneous line-of-sight orientation at the firing time, and supplies the calculated deviation as control signals to the deflection apparatus, which pivots the first laser beam by pivoting angles (xcex1z, xcex1x) relative to the instantaneous line-of-sight orientation at the firing time, with the angles corresponding to the control signals. The trajectory calculator either calculates the flight time of the fictively fired projectile for the target range (r) calculated by the range calculator, and compares it to the time that has passed between the firing time and the reception of the reflected laser pulses of the first laser beam, or uses the trajectory data to calculate the theoretical pivot angles of the first laser beam relative to the instantaneous line-of-sight orientation at the firing time, and compares the calculated pivot angles to the actual pivot angles (xcex1z, xcex1x) of the first laser beam relative to the instantaneous line-of-sight orientation at the firing time, and if the compared angles match within a tolerance range, the trajectory calculator generates an activation signal for transmitting the second laser beam in the transmission direction last traversed by the first laser beam.
The method of the invention, as well as the apparatus of the invention, has the advantage that measuring the target with local resolution is omitted, in addition to range measurement, so no complex, locally-resolving detector or laser scanner is required on the gun barrel. The target is measured solely with respect to its range from the gunxe2x80x94with moderate precisionxe2x80x94and not additionally with respect to the precise target position. The local information lies directly in the impact point of the second laser beam, which has been corrected in elevation and lead. In the case of a target cluster, that is, a plurality of targets located close together, the problem of target separation that occurs in a local resolution of the target is eliminated, and in the pure range measurement, only a slight measuring imprecision occurs, which only leads to minor errors of secondary significance. The second laser beam, comprising encoded laser pulses, always impacts where the fictively fired or virtual projectile also impacts, so the target resolution of the target field itself is performed naturally. The elimination of the necessity to perform a local measurement of the target simplifies the apparatus for firing simulation, and makes it considerably less expensive to produce.
The apparatus of the invention for firing simulation is compatible with 1-way codes and 1-way passive systems having a corresponding detector arrangement, because, unlike in the known 2-way simulator, no target courses of the point of burst must be transmitted to the target. To this point, the apparatus of the invention has been the only multipath simulator for large firing ranges for the internationally-employed MILES (Multiple Integrated Laser Engagement System) code.
Because only the first laser beam must traverse twice the target range, the attainable range is only limited by the power of the laser used for the second laser beam comprising encoded laser pulses, the laser preferably being designed for a wavelength of 905 nm in order to be compatible with existing systems, such as MILES, and its power being limited by the limit for visual detectability. The laser generating the first laser beam, in contrast, can be designed independently of the laser of the second laser beam, and have a particularly visually-detectable wavelength, for example in a range between 1500 and 1800 nm. The limit for visual detectability is therefore about 15,000 times higher than at the wavelength around the aforementioned 905 nm. The laser power can be correspondingly high. In the use of such a high-power, visually-detectable laser, the otherwise standard plurality of reflectors on the target can be omitted, which has a favorable effect on the manufacturing costs of the firing-simulation apparatus.
Advantageous embodiments of the method according to the invention, with advantageous modifications and embodiments of the invention, are disclosed. Moreover, advantageous embodiments of the apparatus according to the invention, with advantageous modifications and embodiments likewise are disclosed.
According to an advantageous embodiment of the invention, the deviations of the trajectory from the instantaneous line-of-sight orientation, the so-called target direction, at the firing time, and the derived pivoting-angle values for the first laser beam, are determined in the vertical or elevation direction. Only if a spin behavior, that is typical for the selected ballistic projectile, is to be taken into consideration in a refined trajectory calculation, are the deviations of the trajectory from the target direction at the firing time determined in azimuth. Pivoting-angle values for the pivoting of the first laser beam are also determined in the horizontal direction from the deviations.
According to another advantageous embodiment of the invention, in the use of a laser transmitter with two separate lasers for generating the two laser beams, the beam cross section of the laser is selected such that the surface on the target that is illuminated by the first laser beam is significantly larger than the surface illuminated by the second laser beam. Hence, it is only necessary to provide one reflex-reflector unit on the target, the unit having, for example, four reflex reflectors that are disposed in pairs diametrically opposite one another, and cover a 360xc2x0 angle with their receiving sectors. The divergence of the first laser beam for the range measurement is minimized for a high radiation density at the target to permit large ranges.
If, in accordance with a further embodiment of the invention, a plurality of reflex reflectors is mounted on the target in the manner of a belt, the divergence is selected such that, with a predetermined minimum range, the first laser beam that illuminates the target at an arbitrary location impacts at least one reflex reflector. Whether it is necessary to use reflex reflectors is a function of the type of laser used to generate the first laser beam. With the 1500-nm diode lasers that are currently available, the power is inadequate to permit ranges of 4000 m or more without reflex reflectors. With high-power Er:glass lasers or Raman-shifted Nd:YAG lasers, however, the reflex reflectors can be omitted, because the diffuse reflection of the target is sufficient. The omission of the costly reflex reflectors has the potential to reduce costs significantly. In this case, the divergence of the first laser beam is made very small in order to attain high intensities at the target. The divergence of the first laser beam can be smaller than that of the second laser beam. The advantage of the small divergence is that only a few interfering reflections occur due to objects located in the immediate vicinity of the target, such as trees, shrubs, etc.
According to yet another advantageous embodiment of the invention, the gun-side detector that is fixedly connected to the barrel has receiving optics, whose receiving divergence is at least as great as the deflection range of the laser beams that is caused by the deflection apparatus. As an alternative, the detector can have adjustable receiving optics, whose receiving divergence corresponds to the effective beam cross section of the first laser beam, i.e., the cross section of the illuminated surface on the target, and the receiving optics are coupled to the deflection apparatus such that it is pivoted by the same pivoting angles as the first laser beam. The advantage of this alternative embodiment is an improved S/N ratio, because the receiving divergence can be selected to be smaller. A drawback is the higher opto-mechanical outlay.
A highly-sensitive avalanche photodiode or a PIN diode having a bandpass filter can be used as a detection element in the detector. The narrow receiving angle and the large laser wavelength permit a very sensitive range measurement.
With low range requirements, or with the provision of more reflex reflectors on the target, according to an advantageous embodiment of the invention, the two laser beams can be generated with a single laser, whose visually-detectable wavelength is preferably at 905 nm in order to be compatible with other systems. Because of the small beam diameter, as stipulated by power and target precision requirements, a large number of reflex reflectors is required for larger targets. As an alternative to reflex reflectors, the laser beam can be scanned in azimuth.
The invention is described in detail below by way of an embodiment of an apparatus for firing simulation, which is illustrated in the drawings.